Smith being the 13th Doctor is interesting insofar that Moffat clearly wanted to do something radical with the format, and he has, he’s cheated of course(but let’s be fair he’s had some help from RTD in that respect) but he has/will do something quite polarising. I’m not sure about it myself.
Obviously Eleven has made reference to regenerating, but I guess the following all have a get out.
Let’s Kill Hitler: He considers regeneration as an option. Now it may be that he’s so blotted the War Doctor out of his mind that he isn’t even counting him, and/or it may be that he hadn’t at this stage realised that it cost a regeneration to remain Ten. Interesting to note that the Tardis interface advises that ‘Regeneration is disabled.’
His ‘death’ at Lake Silencia: Whether it’s him regeneration or the Teselecta this can be explained. If it’s the Teselecta that it may be the Doctor programmed it to make it look like he was regeneration because he knew River would expect this, or because even if you can’t regenerate your body will still try (this works for it’s it is the Doctor originally).
The Name of the Doctor: How can eleven think of himself as the last Doctor when Capaldi comes swooping in in his Tardis at the end? I guess he could forget in the same way Hurt and Ten will forget him, but this doesn’t explain the curator and…
..ok my head officially hurts now!